Atlas Copco Air Contact Hardware Manual page 13

5.2.2 Flash EPROM
For code memory a Flash EPROM is provided. Flash EPROM's have the property that they are in circuit
programmable. This allows to program the controller without opening it and making it easy field updates.
Following device sizes are provided in the controller design:
•
256
•
512
•
1024
This two types are called bottom boot sector Flash EPROM because they consist 1x16kByte, 2x8kByte,
1x32kByte and the rest are 64kByte sectors.
To provide that three different types of Flash EPROM on the PCB do not cause additional costs and
allows to adapt the right size. Which type will be used will be decided during the project and it depends on
device costs and size of application software.
Technical data
sector erase time
chip erase time
byte programming time
chip programming time
access time read cycle
1)
The data above specifies only the time required from the Flash EPROM. For a complete software
download the time to transfer the data (baudrate), handshaking and check sum control should be added.
The whole downloading time depends on the software concept too.
•
Flash EPROM has a limited number of program/erase cycles per sector. It is not suitable for data
memory that are updated every PLC cycle. The manufacturers of this devices guarantees the
minimum of 1 million program/erase cycles.
•
Flash EPROM allows only an erase operation for a whole sector (16kByte or 64kByte) and not
for a byte.
•
the program sequence for the Flash EPROM depends on manufacturer. The software must
support different types.
•
To the Flash EPROM only 16 Bit access (word) is allowed.
5.2.3 SRAM
The SRAM (Static RAM) is provided as data memory. Of course it could be used also as code memory
with the C164CI microcontroller.
128 kByte only 124 kByte useable
Technical data
access time read/write
The data bus to the SRAM is 8 Bit wide.
kByte Typ: 29F200
kByte Typ: 29F400
kByte Typ: 29F800
1)
typ.
1)
typ.
1)
typ.
1)
typ. 3.6
typ. 250
typ. 250 ns
Air Contact Hardware Manual
1 s
8 s
7 µs
s
ns
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